In my ever ongoing hunt for 6800 software I came across an old FLEX disk with this program on it that looked interesting.
adventur.cmd
An executable file and by the name it looked like some kind of adventure. It immediately caught my attention but it crashed when I tried running it on my MC3 computer. Still, I was curious about it. Using my cmd2bin converter I was able to extract one continuous chunk of binary data from the CMD file.
adventur.bin - load address $0100-$32F1
A quick look with a hex editor revealed ASCII contents that definitely looked like a classic text based adventure game. Now this was getting exciting. Further digging and disassembly revealed a quite elaborate program that definitely was a game. A game called "Calixto Island Adventure" made by Mark Data Products in 1981. The text only version of the game was created by Ron Krebs. I believe that may be the one I'm having here. The 6809 and 8086/8088 source has been released to the public by Bob Withers and Steve O'Dea, creators of the CoCo and IBM/PC versions of the game, so I figured it would be okay to distribute this one as well. This is the first and only 6800 release of the game I've ever seen. Below is my disassembled version. I've translated the external FLEX labels. The program relies heavily on jump tables that I have not translated to proper labels so the code can not be re-located as it is right now but I did not need to do that. The code loads and begins at $0100 which is pretty standard for most 6800 programs. Digging into the code too much might also spoil the game play for me so I did not want to risk that!
adventur_disasm.asm
The use of the zero page made it clear why the code did not run on my MC3. The 6303 CPU I use have the first 32 bytes of zero page reserved by internal registers and the Calixto Island code had variables starting at $0000 and up. Relocating them 32 ($20) bytes up was the only thing needed to get the game running on my system!
I'M IN PROFESSOR LAGARTO'S COMFORTABLE STUDY.
VISIBLE ITEMS HERE ARE:
A FLIGHT OF STAIRS.
A ROLLTOP DESK.
AN ORIENTAL RUG.
AN ANTIQUE TABLE.
WELCOME TO THE CALIXTO ISLAND ADVENTURE
TELL ME WHAT TO DO !
The game it self is a classic VERB+NOUN text adventure. User give commands like "OPEN DOOR", "GO PASSAGE", "GET RUG" or "PRESS BUTTON". There is also the possibility to save the current progress to a FLEX file which is a really nice feature given the age of the program. The user can choose the file name of the saved game to load or save. It's also possible to change the save file name during the game. To save a game simply give the command "SAVE GAME". To stop playing say "QUIT". To see what items you are carrying use the command "TAKE INVENTORY". The file access is based on FLEX 2.0 routines so I have converted my MC3 version of the game to use my MCFS2 instead for file access. It was a good practice run for this type of conversion.
adventure_mc3.asm
Above is the MC3 version of Calixto Island Adventure. I have located the FLEX LOAD and SAVE routines and added new ones. This file should be a good start if you want to convert the game for your own system.
Happy adventuring!

You are awesome man - nostalgia :)
I'm on channel 22 sometimes if you wanna give me a hauler ;)

by Daniel 2017-09-20 07:37 UTC

Thanks buddy! That's me. Living in the past :)
Not very radioactive unfortunately... Will try to improve that.
Rest of the household isn't that keen on radio noise as I am. I really need a proper shack :)